Method of making spark plugs



April 25, 1933- E. B. NOWOSIELSKI 1,905,600

METHOD OF MAKING SPARK PLUGS Filed Aug. 9, 1930 2 Sheets-Sheet l INVENTOR 20 EdwamBNwmszkZs/a'.

- ATTORNEY April 1933- E. B. NOWOSIELSKI 1,905,600 7 METHOD OF MAKING SPARK PLUGS Filed Aug. 9, 1930 2 Sheets-Sheet 2 3/ gi III 9 INVENTOR fiawamfiJl owaszklsk ATTORNEY Patented Apr. 25, 1933 UNITED STATES PATENT OFFICE EDWARD B. NOWOSIELSKI, OF BLOOMFIELD, NEW JERSEY, ASSIGNOR TO ECLIPSE AVIA- TION CORPORATION, OF EAST ORANGE, NEW JERSEY, A CORPORATION JERSEY OF NEW METHOD OF MAKING SPARK PLUGS Application filed August 9, 1930. Serial No. 474,226.

The present invention relates to ignition devices, and moreparticularly to a spark plug and a method of forming the same.

In the operation of internal combustion engines, various degrees of heat are developed in various types of engines and accordingly spark plugs having different temperature characteristics are desirable for each type of engine to obtain maximum operating efii- 0 ciency thereof. For example, in a high speed engine such as may be used in a racing car or aircraft, where a high degree of heat is developed, a spark plug is required which will remain relatively cold in order to prevent pro-ignition, while in cold running engines a spark plug is required which will stay hot in order to prevent fouling thereof. Consequently a hot engine requires a cold spark plug and a cold engine requires a hot spark O o plug, while engines having intermediate degrees of maximum heat require spark plugs having intermediate temperature characteristics.

In view of the above it has heretofore been common practice to construct several forms of spark plugs having various sizes of insulators, electrodes, etc., in order to obtain the various temperature characteristics required for different engines, or to make one type of plug which was intermediate a cold plug and a hot plug. \Vhere various sizes of plugs are made, manufacturing costs are excessive because different machinery is required for making each size or type, and a single intermediate plug is ineflicient.

One of the objects of the present invention is to provide a spark plug of novel and improved construction which may be quickly and inexpensively adapted for use with an 0 engine having any degree of hotness or coldness.

Another object is to provide a spark plug of novel and improved construction which is both mechanlcally and electrically strong and 43 is capable of long service under severe conditions without mechanical or electrical faults.

Another object of the invention is to provide a novel method of forming spark plugs whereby they may be manufactured in uniform structures of one type but having no definite temperature characteristics and then each plug altered to give it predetermined temperature characteristics.

Still another object is to provide a novel method of forming spark plugs whereby eachplug may be given, in a single operation, different predetermined temperature characteristics in accordance with the temperature conditions to which each plug is to be sub ected.

A further object is to provide a novel method of forming spark plugs whereby they may be manufactured of substantially identical parts and then each plug altered so that it may be adapted for use with an engine having any degreeof hot or cold operation.

A still further object is to provide a novel method of forming spark plugs whereby they may be initially manufactured in large quantities having no definite temperature characteristics and then altered in sets, as desired, to obtain predetermined temperature characteristics for different types of engines.

Other objects and advantages of the invention will appear more fully hereinafter from the following description taken with the accompanying drawings, which illustrates the method of the invention applied to one form of spark plug. It is to be expressly understood, however, that the drawings are for the purposes of illustration and description only, and is not designed as a definition of the limits of the invention, reference being had for this purpose to the appended claims.

In the drawings, wherein like reference characters refer to like. parts throughout the several views,

Fig. 1 is a longitudinal section of one form of the central electrode assembly of a spark plug to which the method of the invention may be applied;

Fig. 2 is a view partially in section illustrating an electrode assembly to which the Fig. 3 is another view of the structures in- I dicated in Figs. 1 and 2 but in which the electrode assembly is provided with different out themethod of the invention and showsa modified spark plug structure partially 1n section;

Figs. 6 and 7 are views similar to F 1g. 5,

illustrating spark plugs which have been formed to provide different temperature characteristics therefor in accordance with the invention; and

Fig. 8 is a left end view of Fig. 7. Referring now to the drawings, Fig. 1 illustrates a novel form of central electrode assembly to which the method of the invention is adapted and comprises an electrode 5 provided at its sparking end with an enlarged head 6 which terminates in a sparking-terminal 7. The other end of the electrode is provided with a collar 8 the purpose of which will be described hereinafter and to whichis attached, in any suitable manner, a terminal mounting 9 for connecting the electrode to a suitable source of high frequency currents. An insulator 10, preferably a mica sleeve, surrounds electrode 5 between the head 6 and the collar 8. A plurality of insulating washers 11, also preferably of mica, surround the electrode 5 and insulating sleeve 1Q adjacent the head 6, said washers initially being of the same diameter. A- plurality of insulating washers-12 surround the other end of the electrode 5 through a substantial portion of its length and rest on a gland 13 which is threaded at 14 so that the complete electrode structure may be assembled with a cooperating member (Fig. 4) which includes the other electrode of the spark plug, and by means of which the spark plu may be inserted in the head of a cylinder 0% an internal combustion engine. Preferably, the insulating washers 11 are assembledon electrode 5 and sleeve 10 so that they abut the head 6. Then a collar 15 having a portion 16 of reduced diameter is passed over the sleeve and electrode so that it bears against the insulating washers 11. Thereafter, memberl? is assembled with the collar 15, and the gland 13 is engaged with the reduced portion 16 of the collar 15 and with the member 17 so that the latter member is enclosed by gland 13 and collar 15. The

member 17 may be, preferably, of soft brass or any other suitable malleable conducting material which readily changes its shape under pressure and may have the form of a pair of frustums or cones having their bases abutting each other as shown in Fig. 1.

The parts thus assembled are subjected to pressure in a suitable press, or in certain instances, the pressure may be applied after the insulating washers 12 have been assembled on the electrode. The pressure is eflective through the internal inclined surfaces of the gland and collar to force the relatively soft member ,17 into intimate-contact with the insulating sleeve 10 whereby the latter is wedged into engagement with the center electrode and a gas seal is formed around said electrode. The flanged collar 8 serves to hold the insulating washers 12 on the electrode and provides means for applying pressure to the assembly as described above. The

pressure thus applied causes the washers to be so compressed that they acquire the characteristics of a homogeneous mass of insulating material which can be cut, carved, or

- a flange 20 which is adapted'to abut said cylinder wall. A substantially cup-shaped electrode 21, the bottom of which is provided with perforations 22 and 23, has its rim bent radially outward at 24 to form a flange engaging a shoulder 25 formed in the body portion 18. Electrode 10 is held in said body by suitable means which, in the form above described, comprises the collar15, the latter being tapered in the method of forming the spark plug to provide an inclined surface which is pressed against the flange 24 by means of the gland 13 when its threaded portion 14 is screwed into the threaded portion of the bod y member 18. There is thus providd a spark plug of novel and improved construction which is adapted,in accordance with the method of the invention to be now described, for use with an engine having any de cc of hot or cold operation.

hereinbefore stated, ,in the operation of internal combustion engines, various degrees of heat are developed by various types of engines. Accordingly, each type requires a spark plug having heat characteristics suitable for the eflicient operation thereof. These heat or temperature characteristics of the plug are determined by the size of the air space 26 surrounding the effective end of the center electrode of the spark plugwhen said electrode is assembled as shown in Fig. 4, and said air space may be varied by forming the insulating washers shown in Fig. 1 so that a portion 27 is provided which fits tightly withinthe cup-shaped electrode 21 to form a seal therewith, and a cut away tapered portion 28 the length of which determines the size of said air s ace. It is, of'course, within the scope 'of t e invention to ada t the method to spark plugs having other onus of electrodes than the cup-shaped form shown in Figs. 1 to 4 of the drawings, in which case the portion 27 of the insulating material would be of a sufficient diameter to form a seal with the inner wall of the body portion 5 18. When the tapered portion 28 is'relatively long the air space 26 is quite large, and

when gases are ignited in the cylinder of the engine a flash passes through the apertures 22 into the chamber 26 and causes the electrode 21 and the body 18 to become hot, the degree of heat imparted to the body portion depending upon the size of said air chamber, that is, the smaller the air chamber, the less heat is imparted to the body member, and vice versa. Consequently, a plug which has a long tapered portion of insulation is what is termed a hot plug and one which has a short tapered portion is termed a ,cold plug, and any degree of hotness or coldness may be prede- I so termined for each plug by varying the length of the tapered portion 28 from a maximum to a minimum, said maximum and minimum being determined by thedistance from the head 6 to the-inclined surface of the collar 3.5 15. In other words, if the portion 27 be made ed and the plug is then imparted a maximum hot characteristic;

Figs. 5 to '8 show a modified spark plug structure for carrying out the method of the invention. This structure differs fromthat shown in Figs. 1 to 4 in the form of the sparking endof the center electrode 5, said end being made in the formof a disc 29integral with said electrode, and difiers further in the form of the cooperating negative electrode carried by the body portion 18 of the negative electrode assembly, which comprises a ring 30 having four 5 internal projections 31 cooperating with the disc 29. In this modified structure the central electrode assemblies are each provided with the same number of insulating washers'll as in Figs 1 to 4, and the.

straight portion 27 and the tapered portion 28 are made witlrthe same dimensions in each assembly, and the negative electrode assemblies are also made identical. The temperature characteristics of each plug of this type may be altered by longitudinally counter boring the body portion 18 of the negativeelectrode assembly to a predetermined depth, as indicated at 32. so that more or less of the straight portion 27 is exposed to the hot gases in the engine cylinder and to the flame produced by the spark occurring between the two cooperating electrodes, and so that the size of the air chamber 26 surrounding the insulating washers 11 is increased or de- 5 creased, respectively. As shown in Fig. -5,

er air space to form a cold spark plug; while i in Fig. 7 only a part of the straight portion is exposed to the flame, thereby providing an air space of intermediate size to form a plug which is intermediate a hot plug and a cold plug. Heretofore, the air space 26 had been varied by various methods, such as increasing or decreasing the amount of insulation afforded by the tapered portion 28 of the present invention and sealing said air space with a metallic washer, which took the place of the straight portion of insulation 27 shown in the drawings. I Consequently, each center electrode had to be assembled in a different manner, that is, a difierent number of washers 11. had to be placed on the electrode 5 to provide the required amount of insulation and a different sized metallic washer had to be provided depending upon the amount of air space which had to be filled in. The latter method is costly inthat difl'erent length electrodes, different amounts of insulation, and different overall lengths are required for each type of plug, a longer time is required in assembling the plug, and different machinery is required in makin the various parts for theseveral types of p ugs The present invention provides a method of forming spark plugs whereby they may be manufactured in large quantities in uniform structures of one type but having no definite temperature characteristics, and then each plug altered to give it predetermined temperature characteristics in accordance with the heat "characterist cs of the engine with which the plug is to be used. In applying the method of theinvention to the structure shown in Figs. 1 to 4, central electrode astermined amount of said insulation is removed from each assembly as, for example, by turning down in a lathe, in accordance with the temperature requirements of the engine with which the plug having the electrode assembly is to be used, and said assembly is combined with a cooperating member as indicated in Fig. 4.

- Fig. 2 illustrates a center electrode as sembly which has been formed in accordance. with the above method so that when assembed with its cooperating member it has a relatively cold characteristic because of the short length of the tapered portion 28 and relatively large sealing portion 27, while the assembly shown in Fig. 3 is relatively V hotter than that shown in Fig. 2 because theassembly tapered portion 28 is longer and the sealing portion 27 is shorter.

In applying the method of the invention I to the structure shown in Figs. 5 to 8, central electrode assemblies having identical structures are provided as before,'and cooperating negative electrode assemblies also having like structures are provided for combining with the central electrode assemblies and thereafter the body portion 18 of. each negative electrode assembly is counterbored to a predetermined depth to increase or decrease the size of the air space surrounding the center electrode in accordance with the tem rature plug is to be used.

There is thus provided a novel method of forming spark plugs which is quite simple, economical, and which reduces the time required in assembling the spark plugs thereby reducing the cost of manufacture, and by means of which the spark plugs may be manufactured in large quantities, all having identical structures, and then the plugs may be altered in sets for various types of engines as desired. There is also provided a spark plug of novel and improved construction which is adapted, by slight alteration in accordance with the novel method, to be used with an engine having any degree of hotness' or coldness. It is to be expressly understood, however, that other forms of spark plugs may be employed in carrying out the method, and reference will therefore be, had

to the appended claims for a definition of the limits of the invention.

What is claimed is: l 1. method of forming spark plugs to adapt them for use with internal combustion engines having different heat characteristics, which consists in making the central electrode assemblies of the plugs identical in 'structure, providing said assemblies with the same number of insulating washers having substantially the same diameters and surrounding the electrodes adjacent their sparking ends, compressing said washers to form a substantially homogeneous mass of insulation, and thereafter applying a cutting tool to the mass to remove a diflerent predetermined amount ofsaid insulation from requirements of the engine with which each plug is to be used.

2. A method of forming spark plugs to adapt them for use with internal combustion engines having different heat characteristics, which consists in making the central electrode assemblies, of the plugs identical in structure, providing the assemblieswith like amounts of insulating material constitutedrequirements of the engine with w ich the each of a different predetermined number of washers to form a cylindrical portion and a tapered portion of varying1 lengths in each in accordance wit the temperature 

